<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">

<script>
function do_test() {
    var canvas = document.getElementById("test");
    var ctx = canvas.getContext("2d");

    var g = ctx.createLinearGradient(0, 0, canvas.width, canvas.height);
    g.addColorStop(0, "red");
    g.addColorStop(1, "green");

    ctx.fillStyle = g;
    ctx.fillRect(0, 0, canvas.width, canvas.height);

    ctx.fillStyle = "white";
    ctx.font = "bold 24px sans-serif";

    ctx.fillText('globalAlpha = 1.0', 20, 40);

    // for reference, use a fill color with alpha instead of global alpha
    ctx.fillStyle = "rgba(255, 255, 255, 0.5)";
    ctx.fillText('globalAlpha = 0.5', 20, 80);

    ctx.fillStyle = "rgba(255, 255, 255, 0.2)";
    ctx.fillText('globalAlpha = 0.2', 20, 120);
};
</script>

</head>

<body onload="do_test()">

<canvas id="test"></canvas>

</body>
</html>
